In this chapter, you will learn about toolchains, how to use and customize them, and how code standards apply to them. A toolchain contains a myriad of tools, such as compilers, linkers, assemblers, debuggers, and a variety of miscellaneous utilities that help to manipulate the resulting application binaries. In this chapter, you will learn how to use the GNU toolchain and become familiar with its features. You will be presented with examples that will involve manual configurations, and at the same time, these examples will be moved to the Yocto Project environment. At the end of the chapter, an analysis will be made to identify the similarities and differences between manual and automatic deployment of a toolchain, and the various usage scenarios available for it.